The risk of flood is on the rise, and experts agree: society isn't ready for what lies ahead.

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Yesterday, the Federal Emergency Management Agency (FEMA) published a landmark investigation on the connections between climate change, population growth and sea-level rise. The study concludes that the amount of the U.S. at risk for floods could increase 45% by 2100, doubling the number of flood-prone properties covered by the National Flood Insurance program and exacting a strenuous toll on the country's Flood Insurance Program.

Like previous government reports, it anticipates that sea levels will rise an average of four feet by the end of the century. But this is what's new: The portion of the US at risk for flooding, including coastal regions and areas along rivers, will grow between 40 and 45 percent by the end of the century. That shift will hammer the flood insurance program. Premiums paid into the program totaled $3.2 billion in 2009, but that figure could grow to $5.4 billion by 2040 and up to $11.2 billion by the year 2100.

The report, which you can read in its entirety here, attributes 70% of the increased risk to climate change and 30% to population growth. Between these two driving factors, the U.S.'s National Flood Insurance Program (NFIP) could be forced to expand its coverage to as many as 11.2 million properties by 2100. That's twice the number it insures today. These projections would put the NFIP, already neck-deep in debt following this past decade's string of devastating storms, in an almost irremediable position. In the absence of serious upheaval to existing policies, the report forecasts NFIP's recovery effort would fall to tax payers and insurance holders – the latter of which, FEMA's study concludes, could expect a 70% spike in their coverage rates.

The NFIP was established to serve as a liferaft to its policyholders. Not the other way around.

Sea levels are on the rise. Is your home at risk of being submerged in the next 10, 50, 100, 300…
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When catastrophic flooding, brought on by relentless rain, wracked central Europe last week, Germany's National Meteorological Service (DWD) spokesman Gerhard Lux emphasized in interviews that weather forecasters were perfectly capable of predicting the heavy rain. The problem, he told reporters, was preparing to cope on the ground.

These floods have demonstrated once again that we have not adapted as best we could. One thing we will probably have to do is return some of what we have taken away from nature. We need more natural flood planes, for instance. And we will have to consider unpopular measures like building bans in risk areas.

And also by Stéphane Isoard of the European Environment Agency: "We build over the land and there is urban sprawl," he told New Scientist last week, "so there is less opportunity for water to infiltrate the soil." It is premature to pin heavy rain on climate change, said Isoard, but when it comes to the devastation wrought by flooding, poor land management is every bit as culpable.

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Criticisms like these are, of course, easily leveled. But action, which is notoriously more difficult to inspire, is doubly complicated in the case of flood-preparedness. Because even if damns are built, even if flood plains are leveled, even if money is reapportioned and the NFIP gets the money it needs to respond to rising flood risk, it may not be enough. As Iain White, director of the University of Manchester's Director of the Centre for Urban and Regional Ecology recently put it: "There comes a point where you can't defend [when there's simply too much water]."

Consider a city like Boston. "In a city so historically connected to water, it will be impossible to relocate people and buildings out of its way as tides creep further inland," writes The Atlantic's Emily Badger in her coverage of a major scientific report, published in February by the Boston Harbor Association, on what sea-level rise could mean for the city throughout the 21st Century and beyond. "Traditionally, coastal communities have tried to protect themselves with berms and sea walls. But those tactics alone won’t keep all of Boston dry in the future."

At left: projected impact of flood depths up to 7.5 feet, a scenario that represents what a 100-year storm surge might look like come 2050, via

This will be the second time this week that I've referred to the following quote from civil engineer Paul Kirshen, co-author of the Boston Harbor Association's report, but it bears repeating.